運用主動偵測對早期發現抗藥性金黃色葡萄球菌移生之探討

Using Active Surveillance in the Early Detection of Methicillin-resistant Staphylococcus aureus Colonization

背景：抗藥性金黃色葡萄球菌（methicillin resistant Staphylococcus aureus, MRSA）是醫療照護相關感染重要的致病菌，病人入院時早期發現移生（或菌落群聚）並實施接觸防護措施，可以減少MRSA傳播。目的：運用主動偵測，以便早期發現和分析入院時MRSA移生病人其住院後鼻腔和環境陽轉及其影響因素。方法：採觀察追蹤研究法，以2010年3月至8月某醫學中心感染科病人為對象，於入院24小時內進行鼻腔及環境的主動採檢，住院後則每週一、四採檢，直到病人轉出、出院或死亡為止。結果：本研究共收案239人，其中182人納入資料分析。入院24小時內的鼻腔培養陽性佔53.3%，環境培養陽性為7.1%；住院之後的鼻腔培養MRSA由陰性轉變為陽性有50人（27.4%），平均9.2天；環境培養轉為陽性則是35人（19.2%），平均11.4天。MRSA院內感染的發生密度由0.47‰降至0.19‰。鼻腔MRSA移生由陰性轉變陽性之顯著因素，經單變項分析有鼻胃管和類固醇使用（p < .05），多變項分析則包括病人入院時有壓瘡感染為2.68倍，類固醇使用為2.81倍，以及病人每多住一天的風險增加6%。結論：主動偵測可以早期發現MRSA移生並採取防護措施，進而降低院內MRSA感染。照護病人破損的皮膚，尤其是壓瘡時，應戴手套和執行手部衛生等接觸防護措施；同時施行環境清潔管理，以降低MRSA在病人、工作人員和環境之間傳播。

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the principal pathogens implicated in hospital-acquired infections. Active surveillance of patients with MRSA colonization at admission may reduce the spread of the MRSA through contact precautions.Purpose: This study applies active surveillance to the early detection of MRSA colonization and to the determination of the risk factors of MRSA colonization.Method: A prospective cohort study was conducted at a medical center in North Taiwan from March 2010 to August 2010. Participants were recruited from among patients admitted to an infection department who were under active surveillance for culture within the 24-hour period following admission. Nose and environment samplings were taken every Monday and Thursday until participants were transferred, discharged, or expired.Result: This study enrolled 239 patients, with 182 included in data analysis. Positive nasal cultures were found on 53.3% of admitted patients during the initial 24-hour period, with 7.1% generating positive environmental cultures. During the nose and environment sampling phase, 27.4% and 19.2% of participants, respectively, generated positive nasal and positive environmental cultures. The average number of days required to provide a positive culture were 9.2 days for nasal cultures and 11.4 days for environmental cultures. Incidence density of nosocomial MRSA infections reduced by 0.47 per mille to 0.19 per mille. Univariate analysis identified using a nasogastric tube and using steroids as two statistically significant risk factors for positive nasal MRSA colonization (p ＜ .05). A multivariate analysis of risk factors showed a 2.68-times higher risk in participants admitted with pressure sores and 2.81-times higher risk in those who used steroids. The risk of participants acquiring MRSA during their stay was 6% per day.Conclusions: Active surveillance facilitates the early detection of MRSA colonization. Healthcare professionals should wear gloves and adhere to hand-hygiene and contact-precaution protocols when caring for damaged skin, especially pressure sores. Further, healthcare professionals should implement clean environment practices to control the spread of MRSA.